80449715 story Caltech Astronomers Say a Ninth Planet Lurks Beyond Pluto (sciencemag.org) 258 Posted by Soulskill on Wednesday January 20, 2016 @12:55PM from the nemesis-returns dept. sciencehabit writes: The solar system may have a new ninth planet. Today, two scientists announced evidence that a body nearly the size of Neptune — but as yet unseen — orbits the sun every 15,000 years. During the solar system's infancy 4.5 billion years ago, they say, the giant planet was knocked out of the planet-forming region near the sun. Slowed down by gas, the planet settled into a distant elliptical orbit, where it still lurks today. Here's a link to the full academic paper published in The Astronomical Journal.